Do-It-Yourself Climate Modeling

If you're curious about what 16 reputable climate models say about the future of your corner of the planet, check out the Climate Wizard, a site that lets you use model simulations individually or as an "'ensemble average" to show how future temperatures and precipitation may change around the world as greenhouse gas concentrations continue to increase. Regardless of what you think about human influences on climate or the ability of such models to simulate them, having such a large number of projections available in one spot allows for some interesting comparison-shopping.

You can select low, moderate, and extreme greenhouse gas emission scenarios to drive the models, focus on specific months or seasons, and zoom in on maps to see what happens in any given nation or state by the 2050s or 2080s AD. Areas that register a past or future warming or drying trend are shaded in yellows, oranges, and reds while cooling or wetting zones are shown in darkening greens and blues. You can also find summaries of historical weather trends since the 1950s, and numerical graphs of the data are also available.

For example, much of the greatest anticipated future warming is in the Arctic, and most models show the southeastern United States and Mediterranean region becoming drier in the future while central Asia and northeastern Africa become wetter.

Before you partake of the Climate Wizard, however, here are some things to keep in mind:

1. Nobody yet knows which of these simulations are the most accurate, so take them with a grain of salt. This is especially important for precipitation, which is devilishly hard to model and yields less consistent results than temperature does.

2. In general, results that encompass large geographical areas and long time scales may be more likely to be correct than small, short-term ones.

3. An ensemble average of all the model outputs is not necessarily more reliable than the output of any single model because an average of the whole bunch may simply obscure the results from most reliable one.

Despite such limitations, these models do a good job of showing how greenhouse gases can affect temperature in general. Compare the results of a moderate (B1) carbon emissions scenario to those of an extreme (A2) scenario and you'll see how heat-trapping gases raise temperatures more and more as carbon dioxide concentrations rise. The model outputs also show that different regions are likely to respond differently while global average temperatures rise, and that precipitation patterns are affected as well.

For more information on Climate Wizard and climate modeling in general, see here and here.